This invention relates to a process for the pre-treatment of contaminants from a flowing waste fluid, and more particularly to an apparatus and method utilizing a macerator, ozone (O.sub.3), a vibrational mixer, a source of hydroxyl radicals (.cndot.OH), strong and weak unpolarized magnetic fields, static discharge units, and ultraviolet (UV) radiation to destroy contaminants.
There have long been various methods and devices for the treatment of biological and chemical contaminants in waste fluids. Large-scale water treatment facilities have been traditionally used for the treatment, removal, and processing of both human and low levels of industrial waste. With increased urbanization these same water treatment facilities have been required to additionally treat complex mixtures of toxic and hazardous material from both private and industrial users. As a result many of these same water treatment facilities are now unable to adequately treat the increased waste flow resulting in accidental or deliberate discharge of untreated material directly into the environment.
To combat the increased flow and more complex nature of current waste fluids, many wastewater utilities throughout the country require industrial generators of organic wastes high in biochemical oxygen demand (food waste, fats and oils, etc.,), recalcitrant xenobiotics (synthetic organic compounds foreign natural biological systems), heavy metals (Cd, Hg, Pb, etc.) and/or highly acid or alkaline pH to pre-treat their waste stream on-site prior to delivery to a waste water treatment facility. Although pre-treatment is required of many industries, liquid wastes generated by hospitals, medical facilities, medical examiners offices, healthcare offices, research facilities, nursing homes, food processing and animal handling facilities, diagnostic laboratories, veterinary clinics, analytical, chemical, microbiological, biotechnology and university laboratories in many instances are not required to pre-treat their collective wastewater stream even though this waste material is known to contain a variety of toxicogenic/mutagenic/teragenic/carcinogenic chemicals and viable, infectious, or genetically altered microbial pathogens. Many of the current pre-treatment units presently in use are expensive to operate, require trained personnel to maintain and require the use of caustic and/or toxic chemicals or expendable filters and cartridges which must be disposed of as a hazardous substance.
Examples of current methods include aeration stripping, ozone, chemical oxidation and reduction, high-energy beam (electron, gamma, and positron) irradiation, incineration, supercritical oxidation, carbon adsorption, filtration, and exposure to ultraviolet radiation. Some of these methods are currently employed, but many have not been generally accepted as standard practices due to their high equipment expense and cost of operation, size of equipment required, generation of toxic by-products and other similarly related problems.
An alternative treatment method is to use ozone in combination with exposure to ultraviolet radiation. Ozone has been used for more than sixty years for water treatment on the European continent. The role of ozone in waste fluid treatment may be classified as both an oxidant and a germicidal compound. There are at least four distinct recognized applications of ozone: (1) as a bactericide; (2) as a viricide; (3) as a powerful chemical oxidant; and (4) as a promoter of hydroxyl radicals when combined with ultraviolet radiation.
The potent germidal properties of ozone have been attributed to its high oxidation potential. Research indicates that disinfection by ozone is a direct result of bacterial cell wall disintegration. This is known as the "lysis phenomenon".
Ozone has several attributes in the treatment of waste fluids such as odor control, color removal, and iron and manganese removal. Ozone oxidizes inorganic substances completely and rapidly, e.g., sulfides to sulfates, and nitrites to nitrates. Of even greater importance is ozone's capability of breaking down complex organic chemicals. Oxidation of organic materials is more selective and incomplete at the concentrations and pH values of aqueous ozonation. Unsaturated and aromatic compounds are oxidized and split at the classical double bonds, producing carboxylic acids and ketones as products. Ozone also exerts a powerful and bleaching action on organic chemicals, which contribute to the color removal in waste fluids.
There are two principal mechanisms by which ozone may react with organic material. The first of these is a direct additive attack in which ozonides and ultimately peroxides are formed together with a splitting of the organic molecule. The other mechanism results from the decomposition of the ozone molecule, which is thought to proceed as follows: EQU O.sub.3 +H.sub.2 O.fwdarw..sub.-- HO.sub.3.sup.+ .cndot..sub.-- +.sub.-- OH.sup.- [ 1] EQU HO.sub.3.sup.+ .cndot..sub.-- +.sub.-- OH.sup.- .fwdarw..sub.-- 2HO.sub.2 .cndot. [2] EQU O.sub.3 +HO.sub.2 .cndot..sub.13 .fwdarw..sub.-- .cndot.OH+2O.sub.2[ 3] EQU .cndot.OH+HO.sub.2 .cndot..sub.-- .fwdarw..sub.-- H.sub.2 O+O.sub.2[ 4] EQU .cndot.OH+.cndot.OH.fwdarw..sub.-- H.sub.2 O.sub.2 [ 5]
These three free radicals, (HO.sub.3 +.cndot.,.sub.-- HO.sub.2 .cndot.,.sub.-- .cndot.OH), especially .cndot.OH, are highly reactive and non-selectively oxidize all sorts of organic matter.
In the application of ozone combined with ultraviolet (UV) radiation, reaction [5] above becomes critically important. When the hydrogen peroxide (H.sub.2 O.sub.2) formed in reaction [5] is exposed to ultraviolet light the following reaction takes place, which leads to the generation of additional hydroxyl radical (.cndot.OH). EQU H.sub.2 O.sub.2 +hv.fwdarw..sub.-- 2.cndot.OH [6]
Many of these combined ozone/UV treatment systems are limited in their commercial application due to their relatively small scale and ability to deliver an adequate concentration of ozone and level of UV radiation sufficient for bacterial inactivation and chemical destruction. Typically these combined treatment systems have only been utilized for "in-home" domestic potable water treatment to remove taste and odor problems resulting from chlorination. As a result there has been considerable interest in improving ozone/UV treatment systems and techniques to allow for the treatment of more complex waste fluids at higher flow rates.
For example, U.S. Pat. No. 4,028,246 to Lund, et al, proposes a method by which a sewage effluent is simultaneously exposed to ozone and ultraviolet radiation followed by activated carbon adsorption filtration. The waste stream is then polished utilizing gamma irradiation.
Hellman, U.S. Pat. No. 4,687,574 describes a mobile water treatment device wherein the water is collected in a holding tank and subsequently passed through a screen to remove gross solids. The waste stream is then chemically treated in a flocculator to precipitate additional dissolved solids from the waste stream. The resulting mixture is then fed into a separator comprised of small plates or laminates to remove the precipitated solids. The remaining liquid waste is then sparged with ozone.
In U.S. Pat. No. 4,793,931, Stevens, et al, reveals a process for the treatment of waste containing solid or liquid phase contaminants The process includes chemical extraction of the waste contaminants using a perfluorinated solvent, separation of the perfluorinated solvent, and treatment of the remaining waste with a combination of ozone and exposure to UV radiation.
Johnson, et al, U.S. Pat. No. 4,563,286 describes a water purification system that employs the use of ionized allotropic forms of oxygen gas, ozone, and UV radiation. In this system the water being treated is simultaneously exposed to all three treatment techniques.
In its simplest form, Aqueda, et al, U.S. Pat. No. 5,266,216 shows a domestic water treatment apparatus in which only ozone is bubbled through the water column. Whereas, in U.S. Pat. No. 4,273,660, Beitzel exposes wastewater to ozone and UV radiation, while the wastewater is held in a cylindrical chamber containing a tubular UV lamp.
More complex treatment systems include a system designed by Feather, U.S. Pat. No. 4,414,924 for the removal of hydrogen sulfide and iron from well water. In this system, the treatment involves bubbling ozone and oxygen from a lower chamber through dilution control orifices to an upper chamber. In a counter current fashion the water flows into the lower chamber where the remaining traces of hydrogen sulfide are removed via additional ozone sparging. Inducing a vortex in the water column as it flows from the upper chamber to the lower chamber enhances effective contaminant oxidation. Further iron removal and water softening is achieved by passing the water stream through a magnetic field Thomas, Jr., U.S. Pat. No. 4,915,846 discloses a device, which precipitates dye particles from wastewater using an applied electric field. In U.S. Pat. No. 5,092,998, Satoh, also utilizes a strong electromagnetic field for the treatment of aqueous solution.
Furness, et al, in U.S. Pat. No. 5,417,852 describes a multi-step treatment system for removing contaminants from waste fluids. The method includes contacting a waste fluid stream with a promoter of hydroxyl radicals to entrain the promoter of hydroxyl radicals in the waste fluid stream, passing the waste fluid stream having the promoter of hydroxyl radicals entrained therewithin along a substantially tortuous path to allow the promoter of hydroxyl radicals to well within the waste fluid stream and to further entrain the promoter of hydroxyl radicals in the waste fluid stream, and irradiation the waste fluid stream with ultraviolet radiation.
Industrial wastewater treatment is described by Coate, et al, in U.S. Pat. No. 5,679,257. A wastewater treatment system is illustrated which can be configured to be portable and which minimizes the quantity of solids to be disposed of through the use of ozone for contaminant reduction to basic elements after the pH value of the wastewater to be treated is properly adjusted. This ozone, in one stage, is combined with ultrasound to cause coagulation and precipitation. In another stage ozone and ultraviolet light are used in a reduction process. Ion alignment using an electromagnetic field and an electrochemical flocculation process to which the wastewater is subjected causes further coagulation and precipitation. Throughout the "treatment train" filters are utilized to remove precipitated particulate matter.